[llvm-commits] CVS: llvm/lib/Transforms/Scalar/Reg2Mem.cpp
Andrew Lenharth
alenhar2 at cs.uiuc.edu
Wed Nov 9 17:58:50 PST 2005
Changes in directory llvm/lib/Transforms/Scalar:
Reg2Mem.cpp added (r1.1)
---
Log message:
The pass everyone has been waiting for!
Reg2Mem
for fun you can opt -reg2mem -mem2reg
---
Diffs of the changes: (+79 -0)
Reg2Mem.cpp | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 79 insertions(+)
Index: llvm/lib/Transforms/Scalar/Reg2Mem.cpp
diff -c /dev/null llvm/lib/Transforms/Scalar/Reg2Mem.cpp:1.1
*** /dev/null Wed Nov 9 19:58:48 2005
--- llvm/lib/Transforms/Scalar/Reg2Mem.cpp Wed Nov 9 19:58:38 2005
***************
*** 0 ****
--- 1,79 ----
+ //===- Reg2Mem.cpp - Convert registers to allocas -------------------------===//
+ //
+ // The LLVM Compiler Infrastructure
+ //
+ // This file was developed by the LLVM research group and is distributed under
+ // the University of Illinois Open Source License. See LICENSE.TXT for details.
+ //
+ //===----------------------------------------------------------------------===//
+ //
+ // This file demotes all registers to memory references. It is intented to be
+ // the inverse of PromoteMemoryToRegister. By converting to loads, the only
+ // values live accross basic blocks are allocas and loads before phi nodes.
+ // It is intended that this should make CFG hacking much easier.
+ // To make later hacking easier, the entry block is split into two, such that
+ // all introduced allocas and nothing else are in the entry block.
+ //
+ //===----------------------------------------------------------------------===//
+
+ #include "llvm/Transforms/Scalar.h"
+ #include "llvm/Transforms/Utils/Local.h"
+ #include "llvm/Pass.h"
+ #include "llvm/Function.h"
+ #include "llvm/Module.h"
+ #include "llvm/BasicBlock.h"
+ #include "llvm/Instructions.h"
+ #include "llvm/ADT/Statistic.h"
+
+ #include <list>
+
+ using namespace llvm;
+
+ namespace {
+ Statistic<> NumDemoted("reg2mem", "Number of registers demoted");
+
+ struct RegToMem : public FunctionPass {
+
+ bool valueEscapes(Instruction* i) {
+ BasicBlock* bb = i->getParent();
+ for(Value::use_iterator ii = i->use_begin(), ie = i->use_end();
+ ii != ie; ++ii)
+ if (cast<Instruction>(*ii)->getParent() != bb)
+ return true;
+ return false;
+ }
+
+ virtual bool runOnFunction(Function &F) {
+ if (!F.isExternal()) {
+ //give us a clean block
+ BasicBlock& bbhead = F.getEntryBlock();
+ bbhead.splitBasicBlock(bbhead.begin());
+
+ //find the instructions
+ std::list<Instruction*> worklist;
+ for (Function::iterator ibb = F.begin(), ibe = F.end();
+ ibb != ibe; ++ibb)
+ for (BasicBlock::iterator iib = ibb->begin(), iie = ibb->end();
+ iib != iie; ++iib) {
+ if(valueEscapes(iib))
+ worklist.push_front(&*iib);
+ }
+ //demote escaped instructions
+ NumDemoted += worklist.size();
+ for (std::list<Instruction*>::iterator ilb = worklist.begin(),
+ ile = worklist.end(); ilb != ile; ++ilb)
+ DemoteRegToStack(**ilb, false);
+ return true;
+ }
+ return false;
+ }
+ };
+
+ RegisterOpt<RegToMem> X("reg2mem", "Demote all values to stack slots");
+ }
+
+ // createDemoteRegisterToMemory - Provide an entry point to create this pass.
+ //
+ FunctionPass *llvm::createDemoteRegisterToMemoryPass() {
+ return new RegToMem();
+ }
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